Can I use the costomized rasterization algorithm by GLSL?

Hi.

I'm not good at English well, so please understand me.

I am beginer, study OpenGL for studying graphics performances.
OpenGL Architecture has the Vertex Processor and Fragment Processor. So, we can program in the two cases.
Then, I would like to use the customized rasterization algorithm. But, I don't know how to do it.

You can, but only by co-opting a fragment shader for that purpose. Basically, you draw a screen-space polygon over the area where the rasterized primitive will appear, then use `discard` and other fragment shader mechanisms to "rasterize" your actual primitive.

But in general, it'll probably be faster to just render a triangular mesh that approximates your surface.

Just out of curiosity, why would you want to use your own rasterization algorithm? Do you have high-performance needs or simply want something rendered on the screen? Before perverting fragment shaders in that fashion, wouldn't a CPU implementation do as well?

I wonder why you would want your own rasterization . I do think it would be cool to do ray tracing with 'real' ambient occlusion algorithms on the fragment shaders, by defining your inworld objects using mathematical surfaces etc.... I wonder what kind of permormance you could get... with a limited amount of objects maybe even real time?